Fix for toggling menu item visibility outside of create/prepare menu

Allow applications to transition from 0=>1+ visible menu items outside
of onCreatePanelMenu/onPreparePanel. Previously, having 0 visible items
at this point would require an invalidation of the options menu.

Bug 6452605

Change-Id: I6cbfc46d0e5ec42b8d78ee516e9b57fdeaf1a890